Monitoring operating conditions in commercial or industrial applications is often crucial to maintaining proper and safe operation of machinery. Material temperature and material erosion (e.g., material wear, material breakdown, etc.) are two conditions that can affect the performance of machines, apparatus, or systems. Continuous operation or repeated use often elevates the temperature of machines or apparatus. Uncontrolled or overly elevated temperatures may impair the operation of the machine or apparatus. In a similar manner, continuous operation causes material erosion, material wear, material breakdown, etc. of portions of a machine, system, or apparatus. For example, as a fluid flows through an inner bore of a fluid vessel (e.g., a pipe) the fluid causes small particles to break away from the fluid vessel's inner bore surface, which causes the inner bore of the fluid vessel to erode over time. Left unmonitored and/or untreated, such material erosion can lead to unsafe conditions and failure conditions in the machine, system, or apparatus.
The military has similar concerns as those of commercial or industrial entities regarding material conditions such as temperature and erosion. In particular, the military recognizes that operating conditions, such as temperature and erosion, affect the performance and the safe and proper operation of munitions (e.g., weapons). For example, during training exercises and combat scenarios, large caliber guns (e.g., a 5-inch/62-caliber (5″/62) EX 36 MOD 0 gun barrel) installed on Navy ships are often subjected to continuous and repeated operation. To ensure safe and proper operation of the guns, a gun crew must ensure that gun barrels operate within safe operating conditions. Accordingly, the Navy has a critical need to monitor the temperatures at critical areas on the inner bore surfaces of large guns so that a gun crew can act appropriately in cases of misfire. More specifically, in the case of a misfire, the gun crew must know the temperature of the gun barrel bore surface to determine if there is enough time to safely reload the gun (e.g., open the breech, remove the ammunition from the hot gun barrel, and replace the projectile or propelling charge) and fire another projectile or propelling charge before enough heat has transferred from the hot barrel to the projectile. Heat transfer from the gun barrel to the projectile may initiate a cook-off of the projectile, which can result in a misfire.
Traditional methods of determining the temperature of a gun barrel involve using a simplistic chart known as a hot-gun predictor. The hot-gun predictor chart was originally developed for the 5″/54 MK 45 MOD 2 gun, but is often used with other gun types. However, when advanced projectiles and higher energy propelling charges are used, results obtained during gun firing tests and from thermal modeling suggest that the hot gun predictor chart may be either excessively conservative or very non-conservative depending on operating conditions or other circumstances prior to a misfire. Thus, the results from these tests indicate that the hot-gun predictor chart is not well-adapted for use when variables such as ammunition-type are changed.
In a similar manner, measuring erosion of a gun barrel bore surface is often done via predictions and estimates generated using material modeling techniques. More specifically, the material properties (e.g., strength, hardness, etc.) and the shapes of gun barrels and projectiles may be used to model or calculate the rate of erosion of a gun barrel bore based on a number of fired projectiles. Although such modeling techniques can be used to estimate the amount or rate of erosion, the actual erosion often differs due to many factors such as, for example, variations in material, the periodicity of firing, environmental factors (e.g., humidity, ambient temperature, etc.), etc.
Although some measurement or monitoring systems have been developed to measure the temperatures of gun barrel bores, many of those systems are invasive and require access to the gun barrel bore when it is at elevated temperatures. For example, some systems require inserting a thermocouple into the gun barrel bore to obtain a temperature reading. Accessing a gun barrel bore when it is at an elevated temperature is often dangerous and time consuming. In addition, some measurement systems are more suited to operate in an academic or laboratory environment, but may be impractical or cumbersome for use in a real-world environment.